1. Field of the Invention
The invention relates to the recovery of floating materials and more particularly to pollutants floating on the surface of water.
2. Description of Prior Art
The surfaces of bodies of water such as rivers, tributaries, seas and oceans are subject to normal or accidental wastes which burden them with diverse floating solid or liquid wastes. Some wastes may assume outrageous proportions such as, for example, the "black tides" of hydrocarbons which may result from oil spills.
Various recovery apparatus for floating materials utilizing diverse means for receiving the materials on the planar surface of the water are known. Devices utilizing suction, bucket conveyers, shovel pumps, etc. have been proposed. The devices have a slightly submerged inlet which is followed by an elevator bringing the materials received to an evacuation channel which directs them into a decantation and storage container. Very often the apparatus is mounted on a barge which itself carries a decantation container.
To obtain a sufficiently efficient operation it is necessary to concentrate, i.e., to collect the wastes in the form of a sheet, and to move this sheet relative to the inlet of the apparatus. This relative movement which is necessary for the increase of the yield in every case is quite clearly indispensable when the inlet of the apparatus is a simple pocket, more or less flexible, connected by a flexible pipe to a pump means, since to fill the pocket the pocket must be subjected to a veritable "trawling" operation.
When the sheet of floating materials initially has a sufficient thickness and when one is operating in relatively calm water and at a small distance from the bank, the relative movement of the sheet towards the opening can be achieved with a device having long jointed vanes, such as described and claimed in French Patent No. 78 19,943 in the name of the instant Applicant.
In other instances, e.g., very thin pollutant layers and/or agitated surface and/or necessity to operate at a significant distance from the shore, it has been proposed to "sweep" the surface of the water by utilizing a "floating barrier" drawn by its two ends and whose central portion comprises the inlet or opening of the recovery apparatus. The recovery apparatus itself is floated, i.e., it may be mounted on a barge and moves together with the barrier either under its own power when the link to the inlet is flexible or by being pulled more or less freely when this link is rigid.
The barrier assembly can be pulled by pulling means on the shore or by towing the two ends of the barrier. The two ends may be towed separately or together.
However these "sweeping" devices have proven themselves only barely efficient and of very limited use by virtue of the very structure of the floating barriers used.
Until now, in known floating barriers, each of the wings is constituted by the linkage, in a line, of light hollow elements having thin inflatable or rigid walls. These walls are made out of plasticized or rubberized sheets, plastic cloth material, or out of metal.
By using such materials, the barrier has a very substantial transverse surface area thus resulting in a very substantial hydrodynamic resistance to any current moving relative thereto. Consequently, very substantial traction forces are necessary. Furthermore, known devices are very subject to wind forces with respect to the visible or non-submerged potion of the device. If materials having a small thickness are used for the walls, this results in a barrier having only a weak resistance to forces and other shocks thus resulting in the possibility of rupture.
The oblong shape of known elements prevents them from adapting themselves to the irregularities of an agitated surface (waves or splashes) and results in the assembly being very cumbersome which, in turn, does not simplify transportation of the barrier and necessitates long and costly preparations for placing the device in service.
Finally, such a drawn barrier assumes, by virtue of the hydrodynamic resistance, a general shape approximating a U-shaped curve known in French as a "chainette", i.e., having the shape of a pocket having a flattened end resulting in a poor concentration of the floating materials.